-
International Journal of Molecular... Dec 2021The expression of PD-L1 by tumor cells is mainly associated with its immunosuppressive effect. In fact, PD-1/PD-L1 immune checkpoint inhibitors demonstrated remarkable...
The expression of PD-L1 by tumor cells is mainly associated with its immunosuppressive effect. In fact, PD-1/PD-L1 immune checkpoint inhibitors demonstrated remarkable effects in advanced cancer patients including HNSCC. In this context, irradiation is currently being investigated as a synergistic treatment modality to immunotherapy. However, the majority of HNSCC patients still show little improvement or even hyperprogression. Interestingly, there is increasing evidence for additional cell-intrinsic functions of PD-L1 in tumor cells. In previous studies, we showed that PD-L1 has a strong influence on proliferation, migration, invasion, and survival after irradiation. We demonstrated that cellular expression and localization of PD-L1 differed depending on sensitivity to irradiation. Here, we show that PD-L1 is also differentially expressed during cell cycle progression of HNSCC. Furthermore, cellular localization of PD-L1 also changes depending on a particular cell cycle phase. Moreover, distinct observations occurred depending on the general differentiation status. Overall, the function of PD-L1 cannot be generalized. Rather, it depends on the differentiation status and microenvironment. PD-L1 expression and localization are variable, depending on different factors. These findings may provide insight into why differential response to PD-1/PD-L1 antibody therapy can occur. Detailed understanding of cell-intrinsic PD-L1 functions will further allow antibody-based immunotherapy to be optimized.
Topics: B7-H1 Antigen; Cell Cycle; Gene Expression Regulation, Neoplastic; Humans; Protein Transport; Squamous Cell Carcinoma of Head and Neck
PubMed: 34884892
DOI: 10.3390/ijms222313087 -
Viruses Apr 2024The HIV-1 capsid (CA) protein forms the outer shell of the viral core that is released into the cytoplasm upon infection. CA binds various cellular proteins, including...
The HIV-1 capsid (CA) protein forms the outer shell of the viral core that is released into the cytoplasm upon infection. CA binds various cellular proteins, including CPSF6, that direct HIV-1 integration into speckle-associated domains in host chromatin. Upon HIV-1 infection, CPSF6 forms puncta in the nucleus. Here, we characterised these CPSF6 puncta further in HeLa cells, T-cells and macrophages and confirmed that integration and reverse transcription are not required for puncta formation. Indeed, we found that puncta formed very rapidly after infection, correlating with the time that CA entered the nucleus. In aphidicolin-treated HeLa cells and macrophages, puncta were detected for the length of the experiment, suggesting that puncta are only lost upon cell division. CA still co-localised with CPSF6 puncta at the latest time points, considerably after the peak of reverse transcription and integration. Intriguingly, the number of puncta induced in macrophages did not correlate with the MOI or the total number of nuclear speckles present in each cell, suggesting that CA/CPSF6 is only directed to a few nuclear speckles. Furthermore, we found that CPSF6 already co-localised with nuclear speckles in uninfected T-cells, suggesting that HIV-1 promotes a natural behaviour of CPSF6.
Topics: HIV-1; Humans; mRNA Cleavage and Polyadenylation Factors; T-Lymphocytes; HeLa Cells; Macrophages; Virus Integration; Cell Nucleus; Capsid Proteins; HIV Infections; Capsid
PubMed: 38793552
DOI: 10.3390/v16050670 -
Viruses May 2024Equid herpesvirus 4 (EHV-4) is a common respiratory pathogen in horses. It sporadically induces abortion or neonatal death. Although its contribution in neurological...
Equid herpesvirus 4 (EHV-4) is a common respiratory pathogen in horses. It sporadically induces abortion or neonatal death. Although its contribution in neurological disorders is not clearly demonstrated, there is a strong suspicion of its involvement. Despite preventive treatments using vaccines against EHV-1/EHV-4, the resurgence of alpha-EHV infection still constitutes an important threat to the horse industry. Yet very few studies have been conducted on the search for antiviral molecules against EHV-4. A screening of 42 antiviral compounds was performed in vitro on equine fibroblast cells infected with the EHV-4 405/76 reference strain (VR2230). The formation of cytopathic effects was monitored by real-time cell analysis (RTCA), and the viral load was quantified by quantitative PCR. Aciclovir, the most widely used antiviral against alpha-herpesviruses in vivo, does not appear to be effective against EHV-4 in vitro. Potential antiviral activities were confirmed for eight molecules (idoxuridine, vidarabine, pritelivir, cidofovir, valganciclovir, ganciclovir, aphidicolin, and decitabine). Decitabine demonstrates the highest efficacy against EHV-4 in vitro. Transcriptomic analysis revealed the up-regulation of various genes implicated in interferon (IFN) response, suggesting that decitabine triggers the immune antiviral pathway.
Topics: Animals; Antiviral Agents; Horses; Decitabine; Immunity, Innate; Herpesvirus 4, Equid; Fibroblasts; Herpesviridae Infections; Horse Diseases; Viral Load; Cell Line; Virus Replication; Drug Evaluation, Preclinical
PubMed: 38793627
DOI: 10.3390/v16050746 -
Journal of Radiation Research Mar 2024Telomere dysfunction induces chromosomal instability, which is a driving force in the development of cancers. To examine X-irradiation's effect on telomere integrity, we...
Telomere dysfunction induces chromosomal instability, which is a driving force in the development of cancers. To examine X-irradiation's effect on telomere integrity, we investigated X-ray-induced abnormalities in telomere signals detected by fluorescence in situ hybridization (telomere FISH) in mouse embryo fibroblast cells. The abnormalities were categorized as either extra telomere signals (ETSs) or loss of telomere signals (LTSs). The results indicated that low doses (0.3-0.5 Gy) of X-rays significantly induced ETS but not LTS and that ETS induction was saturated at doses above 0.5 Gy. In addition, treatment with hydrogen peroxide also induced ETS but not LTS. To clarify the involvement of radicals in inducing ETS, we examined the effect of ascorbic acid (AsA) on telomere FISH signals and found that pre-treatment with AsA (5 mM, 2 h), but not post-treatment, significantly suppressed the induction of ETS by X-irradiation. Importantly, neither pre- nor post-treatment with AsA affected X-ray-induced chromosome aberrations. These results suggest that oxidative DNA damage induced by radicals is involved in the induction of ETS. Furthermore, combined treatment with aphidicolin, a DNA replication inhibitor, elevated the induction of ETS by X-irradiation. This observation suggests that DNA replication stress, potentially triggered by oxidative DNA lesions within telomeres, may contribute to the induction of ETS resulting from X-irradiation. Based on these results, we propose that ETS is a sensitive biological marker of oxidative DNA damage in telomere structures.
Topics: Animals; Mice; In Situ Hybridization, Fluorescence; Telomere; Oxidative Stress; Chromosomal Instability; Chromosome Aberrations; DNA Damage
PubMed: 38171574
DOI: 10.1093/jrr/rrad102 -
Molecules (Basel, Switzerland) Aug 2019Psoromic acid (PA), a bioactive lichen-derived compound, was investigated for its inhibitory properties against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2),...
Psoromic acid (PA), a bioactive lichen-derived compound, was investigated for its inhibitory properties against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), along with the inhibitory effect on HSV-1 DNA polymerase, which is a key enzyme that plays an essential role in HSV-1 replication cycle. PA was found to notably inhibit HSV-1 replication (50% inhibitory concentration (IC): 1.9 μM; selectivity index (SI): 163.2) compared with the standard drug acyclovir (ACV) (IC: 2.6 μM; SI: 119.2). The combination of PA with ACV has led to potent inhibitory activity against HSV-1 replication (IC: 1.1 µM; SI: 281.8) compared with that of ACV. Moreover, PA displayed equivalent inhibitory action against HSV-2 replication (50% effective concentration (EC): 2.7 μM; SI: 114.8) compared with that of ACV (EC: 2.8 μM; SI: 110.7). The inhibition potency of PA in combination with ACV against HSV-2 replication was also detected (EC: 1.8 µM; SI: 172.2). Further, PA was observed to effectively inhibit HSV-1 DNA polymerase (as a non-nucleoside inhibitor) with respect to dTTP incorporation in a competitive inhibition mode (half maximal inhibitory concentration (IC): 0.7 μM; inhibition constant (): 0.3 μM) compared with reference drugs aphidicolin (IC: 0.8 μM; : 0.4 μM) and ACV triphosphate (ACV-TP) (IC: 0.9 μM; : 0.5 μM). It is noteworthy that the mechanism by which PA-induced anti-HSV-1 activity was related to its inhibitory action against HSV-1 DNA polymerase. Furthermore, the outcomes of in vitro experiments were authenticated using molecular docking analyses, as the molecular interactions of PA with the active sites of HSV-1 DNA polymerase and HSV-2 protease (an essential enzyme required for HSV-2 replication) were revealed. Since this is a first report on the above-mentioned properties, we can conclude that PA might be a future drug for the treatment of HSV infections as well as a promising lead molecule for further anti-HSV drug design.
Topics: Animals; Antiviral Agents; Benzoxepins; Carboxylic Acids; Chlorocebus aethiops; DNA-Directed DNA Polymerase; Herpesvirus 1, Human; Herpesvirus 2, Human; Humans; Lichens; Molecular Docking Simulation; Nucleic Acid Synthesis Inhibitors; Vero Cells; Viral Proteins; Virus Replication
PubMed: 31405197
DOI: 10.3390/molecules24162912